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Smoke haze could affect Singapore again from Oct 20 to 22: Are surgical, cloth masks useful?

The Covid-19 experience has taught Singaporeans to wear a surgical or cloth mask when they are unwell, to lower the risk of respiratory virus transmission.During the ongoing haze episode, residents in Singapore have been seen wearing surgical masks or cloth masks when the air quality, or PM2.5 concentration readings, enter the high or very high band.But are these effective? Do...

AsiaOne Singapore2026-10-20 06:30查看原文 ↗

Smoke haze could affect Singapore again from Oct 20 to 22: Are surgical, cloth masks useful?

The Covid-19 experience has taught Singaporeans to wear a surgical or cloth mask when they are unwell, to lower the risk of respiratory virus transmission.

During the ongoing haze episode, residents in Singapore have been seen wearing surgical masks or cloth masks when the air quality, or PM2.5 concentration readings , enter the high or very high band.

But are these effective? Do they work the same as N95 masks?

PM2.5 measures the concentration of fine particulate matter in the air, and refers to tiny particles that can enter the lungs and bloodstream.

It is considered one of the key pollutants affecting human health during haze episodes.

N95 and equivalent masks are effective against haze and filtering out PM2.5 particles.

And while surgical masks also provide a barrier against larger irritant particles and can reduce discomfort and risk of infection during this time — influenza and haze-related respiratory conditions — they are primarily designed to protect the surrounding environment from a user's spit or mucous.

"If the PM2.5 reading is above 250µg/m3 (very high band) and you have to outdoors for several hours, we would advise that you put out a N95 mask, or equivalent," the Ministry of Health said in an update to its frequently asked questions (FAQ) section on the use of masks and its availability on Monday (Oct 19).

Meanwhile, cloth masks are generally not effective in filtering fine particles, although they could also reduce the discomfort cause by haze by providing a barrier between the wearer's nose and mouth, and larger irritant particles in the air.

"N95 masks were designed to protect the wearer from airborne particles. Studies have shown that they are at least 95 per cent efficient against fine particles that are about 0.1 to 0.3 microns, assuming good fit on the wearer’s face ," the ministry stated.

Can N95 masks be reused?

Infectious disease physician Dr Leong Hoe Nam said in an interview with AsiaOne on Oct 16 that N95 masks can generally be used for one to two days, provided it remains in good condition.

For hygiene purposes, he recommended storing each used mask inside a sealed Ziploc bag, ideally keeping them dry with a desiccant.

Before reusing the mask, Dr Leong said users should also examine the mask and check for signs of damage, such as frayed edges or holes.

They should then do a "seal check" by gently exhaling to feel for air leaks around the edges, or inhaling to check whether the mask draws inwards towards their face.

If there is a leak, users will feel "a gush at the site of the leak" during exhalation, said Dr Leong.

If it passes the test, he advised users to "keep the mask and keep using" it.

On its FAQ section, MOH also stated that N95 masks can be reused, provided it is not soiled or distorted.

This means that masks should continue to provide a good fit.

Dr Pipetius Quah, a respiratory specialist, shared in a video on Oct 16 that N95 masks can be used for up to about five times.

He similarly cautioned that users must first check for fit.

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新冠疫情让新加坡人在身体不适时学会了佩戴医用口罩或布口罩，以降低呼吸道病毒传播的风险。

在持续的雾霾天气中，当空气质量或 PM2.5 浓度读数达到高或非常高水平时，人们可以看到新加坡居民佩戴外科口罩或布口罩。

但这些口罩有效吗？它们和N95口罩的作用一样吗？

PM2.5 测量空气中细颗粒物的浓度，指的是可以进入肺部和血液的微小颗粒。